The present invention concerns bases for vehicle seats and seats including such bases.
More particularly, the invention concerns a vehicle seat base comprising:
first and second slide rails each comprising first and second elements mounted slidingly in relation to each other in a longitudinal direction, one of which is intended to be fixed to the seat and the other to the vehicle, the first element having at least one locking device moveable between:
firstly, a locked position in which said locking device engages with the second element of the slide rail so as to lock the first and second elements relatively to each other,
and secondly, an unlocked position in which said locking device allows the first and second elements to slide relatively to each other, each locking device being loaded elastically towards its locked position,
and a control device able to simultaneously move the locking device of the first and second slide rails to their unlocked position, this control device including operating means which can be actuated by a user so as to act simultaneously on first and second control means which are themselves able to unlock the two locking devices respectively.
The document FR-A-2 777 836 describes an example of such a base which is fully satisfactory with regard to its operation but requires the use of slide rails the moving sections of which have a rather wide upper web, since the slide rails are unlocked by means of a sliding runner which moves horizontally, perpendicularly to the longitudinal direction of said slide rails. This base according to the prior art therefore has the disadvantage of having a control device incompatible with slide rails which have a narrow upper web.
The objective of the present invention is, in particular, to mitigate this disadvantage.
To achieve this objective according to the invention a seat base of the type in question is essentially characterized in that the control device includes first and second pivoted transverse shafts each of which is supported at its two ends respectively by the first elements of the first and second slide rails, each of these first and second control shafts being rigidly connected to one of the control means and being so connected to the control device that actuation of the operating means moves each of the first and second control shafts in a direction corresponding to the unlocking of the locking devices of the two slide rails.
As a consequence of these arrangements the unlocking of the slide rails does not involve the moving of a control means in the transverse horizontal direction, so that, if required, slide rails with a narrow upper web can be used within the framework of the present invention.
In addition, because of its differential effect, the control device of the base according to the invention is able:
to adapt itself to slightly differing unlocking movements between the locking devices of the first and second slide rails, taking account of the manufacturing tolerances of the assembly,
and to adapt itself automatically to the distribution of the force applied to the locking devices of the two slide rails, resulting from the resistance offered by these locking devices to the unlocking movement (for example, if the locking device of one slide rail is slightly blocked during its unlocking movement, the locking device of the other slide rail continues its unlocking movement to the end, after which the force applied by the user is wholly exerted on the blocked locking device, which is generally sufficient to unblock this locking device).
In the preferred embodiments of the invention, one and/or the other of the following arrangements can be used as appropriate:
the control device includes a cable which runs in a non-rectilinear flexible sheath which is controlled by said operating means, the first and second control shafts being rigidly connected to first and second control levers respectively (these may be levers mounted on the control shafts or cranked or U-shaped parts forming part of these shafts), one of which is fixed to the control cable and the other to its sheath and are able to move the first and second control shafts respectively in first and second opposed directions of rotation starting from a rest position when the operating means is actuated;
the operating means comprises an operating lever which extends in the longitudinal direction and is linked to first and second cranks forming part of the first and second control shafts respectively, this operating lever being connected to at least one of the first and second cranks with a certain free play in the longitudinal direction, and these two cranks being orientated in the same direction so that when the operating lever swivels vertically the first and second control shafts swivel respectively in first and second opposed directions of rotation;
the operating lever is pivoted on the second crank but simply passes under the first crank, this operating lever being loaded upwardly against the first crank by a wire bending spring which has:
a first longitudinal end passing underneath the operating lever at a location towards the front of the first and second control shafts,
a second longitudinal end fixed to the second crank,
an intermediate portion which passes above the first crank;
the first and second control shafts are loaded elastically towards their rest positions;
each of the first and second slide rails includes several locking devices each one of which includes a thruster, each of the first and second control means having the form of a connecting arm which pivots with the corresponding control shaft and is articulated to an equalizing bar which is arranged to press on the thrusters of the different locking devices of the corresponding slide rails when the operating means is actuated by a user: this arrangement allows a differentiated force to be applied to the different locking devices of the same slide rail and can adapt itself to differing unlocking movements between the locking devices of the same slide rail;
the first element of each slide rail is constituted by a fixed section able to the fixed rigidly to the vehicle while the second element of each slide rail is constituted by a moving section which is able to be fixed rigidly to the seat and which slides on the fixed section;
the moving section of each slide rail includes a horizontal upper web extended upwardly by a vertical wall which supports the control shafts;
the vertical wall extending from the horizontal upper web of each slide rail has a bracket on which the control shafts are pivoted.
In addition, a further objective of the invention is to provide a vehicle seat including a cushion supported by a base as defined above.